Electric circuit



Feb. 13, 1940. G. H. BUSHWAY 2,189,856

ELECTRIC QIRCUIT Filed oct. 11, 1957 Fig, 1.

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Patented F eb. 13, 1940 UNITED STATES ELECTRIC omom'r.

George H. Bushway, Amesbury, Masa, minor to Electricooker, Inc., Newburyport, Mass a corporation of Massachusetts Application October 11,1937, Serial No. 168,315

Claim.

This invention relates to electric circuits and more particularly to a novel two-part circuit including a heating coil'in one part thereof and a main switch under the control of heat from the 5 coil and adapted in its closed position to shortcircuit the second part of the circuit. Included within the said second part of the circuit is a resistance and an auxiliary switch and means operated from the resistance is provided for causing predetermined opening of this switch. The arrangement is such that under normal conditions the coil will be energized to heating capacity and this heating function will continue to a predetermined point whereat the main switch will he thermostatically opened to a position permitting the passage of electric current through the entire circuit, including the coil and said resistance, and this action will continue until the said means operated from the resistance causes opening of the auxiliary switch. The primary object of the invention is the production of such a twopart circuit adapted to perform the functions above stated and other functions hereinafter more specifically described.

In my Reissue Patent 20,570, I have employed this novel two-part circuit in a cooking machine, the heating coil furnishing the cooking heat and the said resistance being in the form of an electric motor for driving the machine. In such machine, it is required that the motor shall normally remain idle during the heating period and such function is effected by the said main switch which is normally closed to a position short-circuiting the motor-driving portion .of the circuit. 35 It is further required that the motor shall be operated at the end of the heating period and this is accomplished by thermostatically opening the main switch whereby the entire circuit is energized. It is furthermore required that the 40 motor shall be stopped after a. predetermined operation, and'this is accomplished bymotordriven means arranged automatically to openthe auxiliary switch in the motor circuit at the proper time. It is furthermore required that the auxiliary switch shall be returned to its initial position, and this is accomplished by the employment of a shunt to the auxiliary switch in its open position whereby forming a power circuit through the motor when the .main switch is closed, means being provided for moving the auxiliary switch to its initial position after a further predetermined operation of the motor on this shunt circuit; this movement of the auxiliary switch breaking the shuntedcircuit to the motor whereupon the motor stops in its initial position.

A further object of the invention resides in the production of a two-part circuit embodying these novel features.

' These and other features of the invention will be best understood and appreciated from the fol- 5 lowing description of a preferred embodiment thereof selected for purposes of illustration and shown in the accompanying drawing in which,

Figs. 1, 2, 3 and 4 are diagrammatic views of an embodiment of my novel two-part circuit,illustrated in different working positions, and

Figs. 1a, 2a, and 4a are diagrammatic views showing the closed circuits in Figs. 1, 2, and 4 respectively. 7

Referring more specifically to the drawing by reference characters, to and i2 indicate the two wires of the power line. A wire l4 connects the line wire 10 to one end C of a heating coil i5 and a wire l6 connects the other end of the coil to one terminal 18 of a main switch A. The other terminal i9 of this switch is of a resilient nature and is normally in contact with the terminal IS. A wire 20 connects the line wire [2 with the terminal I 9. The circuit as thus far described constitutes the first part of my novel two-part circuit.

Aswire '22 connects the terminal (8 of the main switch A to one side of two resistances comprising a motor 24 and a lamp 25. A wire 25 connects the other side thereof to the switch bar 28 of an auxiliary switch B, the bar being pivoted at 29. A spring 30 connected to one end of the bar normally holds the bar in the position of Fig. 1 wherein it is closed onto 'a contact 32 connected to the line I2 by a continuation of the wire 20. This portion of the circuit extending through the motor and auxiliary switch constitutes the second part of my two-part circuit.

The heating coil I5 is arranged to heat a liquid or. other fluid medium within a container 34. Mounted within the container or otherwise in suitable position to receive heat from the heated medium is a thermostatic element 35 adapted to expand longitudinally upon being heated. A rod 36 connects one end of the thermostat with the top end of a switch block 38 pivoted at 10. The switch terminals l8 and I 9 are mounted on this block with the terminal IS in position to be enaged by a fixed stop 42 when the block is pivoted anti-clockwise, as illustrated in Figs. 2 and 3. The connection to the thermostat is such that longitudinal expansion thereof under the action of heat causes such anti-clockwise movement of the block. This pivotal movement of the block causes opening of the switch, as illustrated, due

' the parts, all circuits are open.

to the forcing of the terminal ll iromeng'agementwiththeterminalliasthestopflis en a ed.

The spring ll normally holds the bar 28 of the auxiliary switch 3 in the position of Fig. 1. A cam 44 driven at reduced speed from the motor is arranged at eachrotation thereof to engage the end 45 of the bar and pivot the bar from engagement with the contact 32 into engagement with a contact connected by a shunt wire 44 to the end C of the heating coil whereby breaking the motor circuit. When the motor is operated from this position (Figs. 3 and 4). through the shunted circuit and the closed switchA (Fig. 4), the spring 30 returns the bar 2! to its initial position (Fig. 1).

The operation of the circuit is substantially as follows:

In the normal position of the circuit (Fig. 1)

the main switch A is closed and the auxiliary switch B is closed onto the contact 32. A circuit is thus established from the power line through the heating coil iii in the closed switch A, the circuit through the motor being short-circuited by the switch'A. The live circuit through the heating coil is illustrated in Fig. la. With the parts in this position the coil heats the medium in the container 34 and this heating continues until the thermostat pivots the switch block 38 to the position of Fig. 2. whereupon engagement of the switch element l9 with the stop 42 opens the main switch A. 1

Opening of the main switch A (Fig. 2) eliminates the said short-circuiting of the motor circuit and establishes the motor circuit through the heating coil and the switch B, the closed circuit of Fig. 2 being illustrated in Fig. 2a. The motor thereupon operates and drives the cam 44 in the direction of the arrow, the limited amount of current now passing through the circuit being insufficient to cause heating of the coil l5. This motor operation continues until the cam engages the switch bar 28 and moves it from the contact 32 to the contact 46, the motor thereupon stopping in the position of Fig. 3. In this position of When the heated medium in the container 34 is cooled sufficiently to cause contraction of the thermostat 35 and movement of the switch block 38 away from the stop 42, the switch A closes (Fig. 4.) The two circuits illustrated in Figs. la and 4a are thereupon established from the line wires I0 and ii. The circuit of Fig. 1a is directly through the heating coil and the circuit of Fig. 4a is through the motor. Heating of the coil and operating of the motor thereupon occurs. The spring 30 however opens the motor circuit to the position of Fig. 1 as soon as the cam 44 leaves the switch bar 28. This leaves the parts in the initial position of Fig. l and from which position the cycle of operations above-described is repeated.

greases I claim:

1. A two-part circuit including a heating coil in one'part thereof and a. motor and an auxili'ary switch in the second part, a main switch in the circuit adapted in closed position to short-' circuit said second part, means operated thermo statically from heat of the coil for opening the main switch, and means for opening the mixiliary switch after a predetermined operation of k the motor.

to short-circuit said second part, means op-.

erated thermostatically from the heat of the coil for opening the main switch to a position permitting the passage of current through the entire circuit including said resistance, and means operated from said resistance for causing pre determined opening of the auxiliary switch.

3. A two-part circuit including a heating coil in one part thereof and a motor and a normally closed auxiliary switch in the second part, a normally closed. main switch in the circuit adapted in closed'position to short-circuit said second part, means operated thermostatically from heat of the coil for opening the main switch, and means for opening the auxiliary switch after a predetermined operation of the motor.

4. A two-part circuit including a heating coil in one part thereof and a motor and an auxiliary switch in the second part, a main switch in the circuit adapted in closed position to shortcircuit said second part, means operated thermostatically from heat of the coil for opening the main switch whereby causing operation of the motorg means for opening the auxiliary switch to stop the motor after a predetermined operation thereof, and a shunt to a portion of the auxiliary switch for cutting the motor into the circuit upon closing of the main switch.

5. A two-part circuit including a heating coil in one part thereof and a motor and an auxiliary switch in the second part, a main switch in the circuit adapted in closed position to short-circuit said second part, means operated thermostatically from heat of the coil for opening the main switch whereby causing operation of the motor, means for moving the auxiliary switch to another pcsition opening the motor circuit after a predetermined operation of the motor, a shunt to a porton of the auxiliary switch for cutting the motor. into the circuit and causing operation thereof upon closing of the main switch, and means for returning the auxiliary switch to its original position after a further predetermined operation of the motor. 

